1. Field of the Invention
The present invention is related to a rolling bearing unit with a rotating speed sensor, for example, in order to rotatably support a vehicle wheel to a suspension apparatus while being capable of detecting the rotating speed of the vehicle wheel.
2. Description of the Related Art
In order to rotatably support a vehicle wheel with reference to a suspension apparatus while being capable of detecting the rotating speed of the vehicle wheel thereby controlling the anti-lock brake system (ABS), or the traction control system (TCS), rotating bearing units with a rotating speed sensor are disclosed e.g. in Japanese Patent First Publications KOKAI No. 3-39161 and No. 3-48768.
The rolling bearing unit with the rotating speed sensor as disclosed in the publications mentioned above is constructed as shown in FIG. 1, and has a hub 1 the axially outer end portion (left end portion in FIG. 1) of which is formed with a flange 2 for supporting a vehicle wheel (not shown). What is meant by the axially outer end portion is the end portion which is located on the outer end side in the width direction when mounted to the vehicle.
The hub 1 has an axially intermediate portion with the outer peripheral surface of which is formed with an inner ring raceway 3a. In addition, an inner ring 4 is fitted onto the outer peripheral surface of the axially intermediate portion of the hub 1 and has an inner ring raceway 3b on its outer peripheral surface.
On the axially inner end portion (right end portion in FIG. 1) of the hub 1, a male threaded portion 5 is formed on its outer peripheral surface and screwed into a nut 6.
What is meant by the axially inner end portion is the end portion which is located on the central side in the width direction when mounted to the vehicle.
The nut 6 screwed onto the male thread portion 5 for clamping presses the axially inner end face of the inner ring 4 to fix the inner ring 4 at a predetermined location on the outer peripheral surface of the hub 1.
The outer ring 7 has a mount portion 9 on its outer peripheral surface for supporting a knuckle (not shown) of the suspension apparatus, and a pair of outer ring raceways 10a, 10b on its inner peripheral surface.
A plurality of rolling members 11 are provided between the outer ring raceway 10a and the inner ring raceway 3a, and between the outer ring raceway 10b and the inner ring raceway 3b, so that the hub 1 is rotatably supported in the interior of the outer ring 7 which is supported by the suspension apparatus through the mount portion 9.
The hub 1 has an axially inner end portion which is protected from the nut 6 so as to be fitted into an annular tone wheel or pulser ring 12.
Fittingly fixed onto the opening portion of the outer ring 7 at its axially inner end is a cover 13 by which a sensor 14 is supported. The tone wheel or pulser ring 12 is faced to the axially outer end face of the sensor 14. Seal members 8 are mounted between the outer peripheral surface of the hub 1 and the inner peripheral surface of the outer ring 7 at its axially outer end and between the outer peripheral surface of the hub 1 and the inner peripheral edge of the cover 13 at its axially inner end, so as to close the openings at the both ends of the space between the inner peripheral surface of the outer ring 7 and the outer peripheral surfaces of the hub 1 and inner ring 4 where the rolling members 11 and the tone wheel 12 are provided.
With the rolling bearing unit with the rotating speed sensor as mentioned above, the vehicle wheel fixed to the flange 2 at the axially outer end portion of the hub 1 is rotatably supported with reference to the suspension apparatus which supports the outer ring 7.
As the tone wheel 12 fittingly fixed onto the axially inner end portion of the hub 1 is rotated with the rotation of the vehicle wheel, the output of the sensor 14 faced to the tone wheel 12 is changed. The frequency of the output change of the sensor 14 is proportional to the rotating speed of the vehicle wheel. Accordingly, the output signal of the sensor 14 is transmitted through the conductive member or lead 15 to a control device (not shown), so that the rotating speed of the vehicle wheel is obtained so as to properly control the ABS and TCS.
It will be noted that the lead 15 to output signals from the sensor 14 is extended axially inward (right in FIG. 1) in the conventional rolling bearing unit with the rotating speed sensor as mentioned above. In this construction, any interference is inclined to be made between the lead 15 and the constant velocity joint 16 to rotate the hub 1 (see FIG. 5 and FIG. 2).
Specifically, provided that the lead 15 is made longer and provided with an electric plug at its end, while a connector provided to the sensor 14 is connected with the electric plug after the rolling bearing unit is mounted to the suspension apparatus, the rolling bearing unit is easily mounted to the suspension apparatus and the convenience upon mounting the rolling bearing unit to the vehicle body is improved. In such a case, however, the electric plug is often prevented from being inserted into the connecter due to the interference with the constant velocity joint 16.
In order to avoid such inconvenience, the rolling bearing unit with the rotating speed sensor as shown in FIG. 2 through FIG. 4 is disclosed in Japanese Utility Model First Publication KOKAI No. 5-43074.
In this second conventional structure, the inner ring 4 has an axially inner end portion which is slightly projected from the axially inner end face of the hub 1 so as to be abutted to the axially outer end face of the constant velocity joint 16 for rotating the hub 1.
In addition, the tone wheel 17 is of a cylindrical shape and has an axially outer half portion which is fittingly fixed onto the outer peripheral surface of the inner ring 4 at its axially inner end portion. In addition, the tone wheel 17 has an axially inner half portion part of which is axially projected from the axially inner end face of the inner ring 4 and formed with a plurality of through holes 24 with a uniform size evenly spaced apart from each other in the circumferential direction.
In addition, seal members 8 are mounted between the inner peripheral surfaces of the outer ring 7 at its axially inner and outer end portions and the outer peripheral surfaces of the hub 1 and the inner ring 4, respectively, so as to close the open end portions of the space provided between the inner peripheral surface of the outer ring 7 and the outer peripheral surfaces of the hub 1 and the inner ring 4 to accommodate the rolling members 11.
A support frame member 18 as shown in FIG. 3 is fitted onto and fixed to the axially inner end of the outer ring 7. The support frame member 18 is of a generally annular shape and made by press-forming a metal plate such as stainless steel, and comprised of a cylindrical mount portion 19 which is adapted to be fitted onto the axially inner end of the outer ring 7, an inwardly flanged portion 20 which is radially inwards bent at right angles at the axially inner edge of the mount portion 19, and a support portion 21 which is axially protected from the axially inner side face (right side face in FIGS. 2 and 3) of the flanged portion 20 at a circumferential location. The support portion 21 has a radially inward opening. A sensor 22 is supported by the support portion 21 and has a detecting portion 23 faced to the axially inner half portion of the tone wheel 17 where the through-holes 24 are formed.
The support portion 21 is provided with a connector 25 on one of the circumferential end walls 26. It will be noted in FIG. 3 that the connecter 25 is protected from that end wall 26, and adapted to receive the electric plug fixed to the end of the lead (not shown in FIG. 3) so as to output the signals detected by the sensor 22. The connector 25 is positioned as in FIG. 4 between the inner and outer peripheral edges 18a, 18b of the support frame 18 and directed in the circumferential direction with reference to the support frame 18.
In the case of this second example in the conventional rolling bearing unit with the rotating speed sensor as mentioned above, the electric plug (not shown in FIG. 4) which is fixed to the end of the lead to take out the signals from the sensor 22 is moved in a circumferential direction of the support frame 18 toward the connecter 25 as shown by the arrow G in FIG. 4 and inserted into the connector 25 for connection between the lead and the sensor 22. It will be noted in this structure that the connection between the electric plug of the lead and the connector 25 is accomplished without interference by the constant velocity joint 16 (FIG. 2).
However, in the case of the second example in the conventional bearing unit, there are still the following problems to be solved.
In order that the sensor 22 is supported by the support portion 21 formed in the support frame 18, generally a thermoplastic synthetic resin is filled in the support portion 21 with the parts of the sensor 22 provided in the support portion 21. The thermoplastic synthetic resin filled in the support portion 21 is solidified encapsulating the parts of the sensor 22.
The connector 25 must be projected from the end wall 26 of the support portion 21 in order to take out the signals from the sensor 22. However, in the case of the conventional structures as mentioned above, no attention is paid to the easy operation for projecting the connector 25 from the end wall 26 of the support portion 21.
In the case of the end wall 26 simply having a through-hole formed for the connector 25, the operation for setting the sensor 22 in the support portion 21 and inserting the connector 25 into the through-hole is inconvenient. Consequently, this may be an obstacle in producing efficiently the rolling bearing units with the rotating speed sensor.
The end wall 26 may be provided with a slot which is opened in the radially inward end edge of the support frame 18, so that the connector 25 can be inserted through the opening of the end edge into the slot. With this construction, however, the support rigidity for the sensor 22 may be insufficient even in the state where the sensor 22 is installed in the support portion 21 and embedded with the synthetic resin filled in the support portion 21.
Specifically, the support portion 21 as illustrated in FIG. 4 is of a sector shape with the larger width on the radially outer side and with the smaller width on the radially, and its support rigidity depends on the end walls 26. Therefore, if the end wall defining the support portion 21 has enough rigidity, the mass of synthetic resin fitted and solidified in the support portion 21 is not displaced in both of the radially inward and outward directions. However, where the slot as mentioned above is formed in the end wall 26 of the support portion 21, the rigidity of the end wall 26 is lowered, and the connector 25 can be displaced radially inward through the slot opening, resulting in that the mass of synthetic resin can be easily displaced radially inward. Consequently, the support rigidity for the sensor 22 may be insufficient resulting in that the rotating speed sensor having such a construction is insufficient in endurance and dependability.